High- and low-affinity interleukin 2 receptors: distinctive effects of monoclonal antibodies.

We previously established several mouse hybridoma cell lines producing monoclonal antibodies against the human interleukin 2 (IL 2) receptor molecule. As they bind to both high- and low-affinity IL 2 receptors, their effects on binding of 125I-labeled IL 2 to high- and low-affinity receptors were examined by Scatchard plot analysis. Two of these monoclonal antibodies, HIEI and H-47, reduced the IL 2 binding affinity of high-affinity receptors from a Kd of 14 to 20 pM to a Kd of 110 to 140 pM, but slightly raised that of low-affinity receptors. These two antibodies scarcely affected the numbers of high- and low-affinity receptors. On the other hand, H-31 completely blocked IL 2 binding to both high- and low-affinity receptors, and H-A26 slightly reduced the affinities of both high- and low-affinity receptors, from 17 pM to 28 pM and from 28 nM to 54 nM, respectively. H-48 had little affect on IL 2 binding to high- or low-affinity receptors. By use of these monoclonal antibodies, the inhibitory effect of IL 2 on growth of an HTLV-I-immortalized T cell line was demonstrated to be transmitted from high-affinity, but not low-affinity, receptors.